The present invention relates generally to receivers, and, more particularly, to an aural annunciator circuit for a receiver, such as a radio receiver portion of a radio transceiver.
A communication system is comprised, at a minimum, of a receiver and a transmitter interconnected by a communication channel. The transmitter of the communication system is operative to transmit a signal upon the communication channel, and the receiver is operative to receive the signal transmitted upon the communication channel.
A radio communication system is a communication system in which the communication channel is comprised of a radio frequency channel. A radio frequency channel is defined by a range of frequencies of the communication spectrum.
The transmitter which forms a portion of the radio communication system includes circuitry for converting information into a signal of a form permitting transmission thereof upon the radio frequency channel. Such circuitry includes modulation circuitry which performs a process referred to as modulation. In such modulation process, information to be transmitted upon the radio frequency channel is impressed upon a radio frequency electromagnetic wave; the radio frequency electromagnetic wave is commonly referred to as a carrier signal. The resultant signal, formed of the combination of the carrier signal and the information, is commonly referred to as a modulated signal. Such resultant signal is also referred to as a communication signal as the modulated signal includes the information which is to be communicated by the transmitter to the receiver.
Radio communication systems are advantageous in that the transmission channel, comprised of the radio frequency channel, does not require any physical interconnection between the transmitter and the receiver. Information, once modulated to form the modulated signal, may be transmitted over large distances.
A two-way communication system is a communication system, similar to that above-described, but which further permits transmission and reception of information at two or more locations. Each location of such two-way communication system contains both a transmitter and a receiver. A two-way radio communication system is a radio communication system similar to that above-described, but which similarly permits both transmission and reception of information at the two or more locations.
In the two-way radio communication system, the transmitter and the receiver positioned at a single location typically comprise a single unit referred to as a radio transceiver, or, more simply, a transceiver. A transceiver capable of simultaneous operation both to transmit and to receive a communication signal is referred to as being capable of full duplex operation.
Cellular radiotelephones and cordless phones are two examples of consumer products comprised of radio transceivers. (Cordless phones are also sometimes referred to as "patio" phones.) Both cellular radiotelephones and cordless phones are advantageously utilized to permit users thereof to communicate therethrough with a user of conventional, telephonic apparatus of a conventional, wireline telephonic network. Because no physical interconnection is required between a cellular or cordless phone and the conventional, telephonic apparatus of a wireline network, such phones permit increased convenience of communication in some instances, and, in other instances, permit communication in instances in which communication would otherwise not be possible.
Cellular and cordless phones are constructed to be operative in manners similar to the conventional telephonic apparatus of the conventional, wireline network. That is to say, both cellular and cordless phones typically include handsets of dimensions at least similar to corresponding dimensions of handset portions of conventional telephonic apparatus. Also, the handsets of cellular and cordless phones also include both speaker portions and microphone portions for conversion of received signals into aural signals and conversion of aural signals into signals suitable for transmission, respectively.
However, because the handsets of cordless phones and the handsets of many constructions of cellular radiotelephones are actually radio transceivers, the handsets of such cellular and cordless phones also include both transmitter and receiver circuitry. As the cellular and cordless phones are operable in manners similar to operation of conventional telephones, cellular and cordless phones oftentimes include annunciator circuitry housed within the handsets thereof to indicate times when a communication signal is transmitted to the cellular or cordless phone.
Operable in manners similar to the operation of a conventional ringer assembly of conventional telephonic apparatus, the annunciator circuitry of the cellular or cordless phone handset is operative to generate an intermittent, aural signal imitative of the ringing of the ringer assembly of the conventional telephonic apparatus. The aural signal generated by the annunciator circuitry housed within the handset housing of the cellular or cordless phone must be of a signal magnitude great enough to provide adequate annunciation of the received signal. That is to say, the volume of the aural signal generated by the annunciator circuitry must be great enough to be noticeable. Because the annunciator circuitry is contained in the handset assembly, the signal level, while of a suitable level when positioned away from a potential user of the cellular or cordless phone may be of an unpleasantly high volume level when the handset is positioned proximate to an ear of such user.
Annunciator circuitry, carried with the handset of the cellular or cordless phone and operable to generate an aural annunciation signal alternately of a normal signal level when the handset of the cellular or cordless phone is likely to be positioned away from the user or of a reduced signal level when the handset of the cellular or cordless phone is likely to be positioned proximate to a user would be advantageous.